The present application describes systems and techniques for regulating access to file system devices in a computer system, for example, a mobile computing platform such as a laptop computer or a hand-held computer.
A typical laptop computer includes one or more file system devices through which files such as application files, data files, operating system files, and the like can be accessed—for example, written or read. Such file system devices include non-volatile data storage devices such as disk drives (e.g., hard disk, floppy disk, zip drive, CD or DVD drive, or non-volatile memory components such as flash cards) as well as other devices such as network interface adapters, or any other network access devices, which typically do not themselves store data but rather serve as a conduit through which file write and/or read requests are communicated to a data storage resource on a network.
Many users rely on their mobile computers for performing computing tasks, for example, running application programs such as word processors, spread-sheet programs, graphic presentation programs and the like, in the absence of the wall-socket AC power sources that are present in virtually all offices and homes. Consequently, a mobile user by necessity often relies on battery power for operating his or her mobile computer. Many users discover, however, that the battery life of their mobile computer is less than they would optimally desire. A mobile user on a long-distance flight may, for example, experience a lapse in battery life, and thus be forced to cease using the computer, while only half-way through the flight. This may be particularly true if the user is operating devices in the mobile computer such as disk drives, which typically exhibit a relatively high level of power consumption compared to other devices in the system.
In an effort to extend battery lifetime, several computer and/or operating system manufactures have developed utilities that enable users to regulate the behavior of their mobile computers while operating under battery power. These utilities can control properties such as screen brightness levels and the length of a hard drive time-out period—that is, the time duration of hard drive inactivity that may occur before the hard drive is forced to power down or otherwise assume a reduced power state.
In addition to the manufacturer-specific implementations of power saving utilities, various organizations have published specifications relating to power management. For example, Intel Corp. and Microsoft Corp. jointly published a power management specification entitled “Advanced Power Management (APM): BIOS Interface Specification,” Rev. 1.2, February 1996. Another specification, “Advanced Configuration and Power Interface Specification,” Rev. 2.0, Jul. 27, 2000, was published jointly by Compaq Computer Corp., Intel Corp., Microsoft Corp., Phoenix Technologies Ltd. and Toshiba Corp.
Details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims.